Dynamic phosphorus mass balance modeling of large watersheds: long-term implications of management strategies

International audienc

Dynamic phosphorus mass balance modeling of large watersheds: long-term implications of management strategies

International audienc

Use of simulation mass balance modeling to estimate phosphorus and bacteria dynamics in watersheds

International audienc

Método para determinação de distribuição de tamanho de microbolhas (DTMB) em sistemas flotação (FAD) para tratamento de águas utilizando a análise de imagem digital Method for measuring bubbles sizes distribution (BSD) in drinking water treatment flotation (DAF) systems by using digital image analysis

O artigo apresenta um método proposto para determinação de tamanho de microbolhas de ar (DTMB) em sistemas de tratamento de água por flotação por ar dissolvido (FAD), utilizando a análise de imagem digital. Adicionalmente, é apresentado um estudo de caso com emprego de unidade em escala piloto. A aquisição das imagens foi realizada com uma câmera digital de 5.1MPixel, acoplada a conjunto de lentes. As imagens de microbolhas foram adquiridas em sistema com escoamento contínuo para eliminar as interferências causadas pela captura de amostras. O tratamento e obtenção das feições foram realizadas com o programa (freeware) "ImageTool". Os resultados apresentaram coerência com os valores reportados na literatura utilizando métodos tradicionais. O sistema mostrou-se eficaz e o método desenvolvido pode constituir ferramenta útil para estudos em outras subáreas de conhecimento.<br>An image analysis method proposed for assessing bubble size distribution applied to dissolved air flotation (DAF) systems for drinking water treatment is presented. Further, a pilot plant investigation is presented. A digital camera together with a group of lens was used. In order to eliminate samples interferences the images were captured in a continuous flow system working in steady state. The freeware ImageTool was applied for treating and obtaining size distribution. Results were presented in good relationship with traditional methods. The role image system showed to be efficient for image capturing and the proposed method may be an useful tool to other researches areas

Diffuse Phosphorus Models in the United States and Europe: Their Usages, Scales, and Uncertainties

Today there are many well-established computer models that are being used at different spatial and temporal scales to describe water, sediment, and P transport from diffuse sources. In this review, we describe how diffuse P models are commonly being used in the United States and Europe, the challenge presented by different temporal and spatial scales, and the uncertainty in model predictions. In the United States for water bodies that do not meet water quality standards, a total maximum daily load (TMDL) of the Pollutant of concern must be set that will restore water quality and a plan implemented to reduce the pollutant load to meet the TMDL. Models are used to estimate the current maximum daily and annual average load, to estimate the contribution from different nonpoint sources, and to develop scenarios for achieving the TMDL target. In Europe, the EC-Water Framework Directive is the driving force to improve water quality and models are playing a similar role to that in the United States, but the models being used are not the same. European models are more likely to take into account leaching of P and the identification of critical source areas. Scaling up to the watershed scale has led to overparameterized models that cannot be used to test hypotheses regarding nonpoint sources of P or transport processes using the monitoring data that is typically available. There is a need for more parsimonious models and monitoring data that takes advantage of the technological improvements that allow nearly continuous sampling for P and sediment. Tools for measuring model uncertainty must become an integral part of models and be readily available for model users